For gear shifting operations in classically configured stepped motor vehicle transmission devices, the following three steps—starting from the old gear—are run through in timed sequence: “disengagement of the old gear”—“selection”—“engagement of the target gear”. Moreover, motor vehicle transmission designs have become known in which the selection or select movement may occur before the disengagement of the old gear. In such configurations, it is provided, for example, that a main control element or shift finger is essentially responsible only for the engagement of gears, and additional geometries take on the function of disengaging gears. In this context, so-called secondary control elements in particular are used for the disengagement function. It may also be provided, for example, that the additional geometries are found on the one hand on central shift shafts and on the other hand on shift mouthpieces that are provided on final control mechanisms or shift forks or shift rails.
The disengagement geometries as a rule are operative in gates in which the shift finger is not active. In this context, it may be provided that a fixed assignment between shift finger and disengagement geometry in this context simultaneously represents an active gear lock. Structural implementations of this approach are therefore also referred to as “active interlock”.
In such an “active interlock”, it is generally provided that the main control element or the shift finger may be moved back into a central or neutral position without disengaging the gear. The select movement is therefore possible before the gear is disengaged.
Such a system, in particular an active interlock system, has become known through German Patent Application 102 06 561 A1. In that document it is further proposed that such a system be used for parallel shift transmissions. In the parallel shift transmission (PSG), different partial transmissions are disposed in different drive train branches. While the functionality of a transmission having only one drive train branch generally requires that only one gear at a time may be engaged in the transmission, in a parallel shift transmission, one gear may be engaged in each of the drive train branches at the same time.
German Patent Application 102 06 561 A1 proposes the provision of a common central shifting shaft for both partial transmissions. For the selection, this central shifting shaft is axially displaceable via electric motor, and for the engagement and disengagement of gears, this central shifting shaft is configured in a rotational manner. To produce the corresponding rotary and axial movements, exactly one electric motor is provided for each. On the shifting shaft, a plurality of secondary control elements are provided for the disengagement of gears as well as—first—a main control element, especially a shift finger, for the engagement of the gears.
In principle, gears could be engaged in both partial transmissions via this one shift finger. However, in order to reduce the axial displacement paths of these shifting shafts, German Patent Application 102 06 561 A1 proposes to provide a separate shift finger and separate secondary control elements for each of the partial transmissions, so that a total of two main control elements or shift fingers and a (correspondingly increased) number of secondary control elements are present there. Furthermore, German Patent Application 102 06 561 A1 proposes controlling the gear change operations or the actuation device via an electronic control device.